Device and method for forming end of coiled spring

ABSTRACT

A coil spring end forming apparatus is provided that includes a pair of horizontally disposed parallel rollers; a mandrel; a stopper that is provided adjacent to the circumferential surface of the mandrel and is moved up or down and rotated integrally with the mandrel; a clamp jig that is provided so as to be movable toward or away from the mandrel and that holds a semi-formed spring in cooperation with the mandrel, and a pusher for pushing the semi-formed spring toward the stopper, wherein in a state in which the axis of the mandrel is positioned between the axes of the parallel rollers and the semi-formed spring, a clamp portion holds the semi-formed spring at the inner side of a triangle formed by the axes of the parallel rollers and the semi-formed spring and rotates around the axis along the winding direction of the semi-formed spring to form a pigtail portion at one end of the semi-formed spring, and a coil spring end forming method is further provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/302,488, filed Nov 25, 2008, which is the U.S. national phase under35 U.S.C. §371 of prior PCT International Application No.PCT/JP2007/060645 which has an International Filing Date of May 24,2007, which designates the United States of America, and which claimspriority to Japanese Patent Application No. 2006-149296, filed on May30, 2006. The International Application was published under PCT Article21(2) in a language other than English. Each of the aforementionedapplications is incorporated by reference herein in its entirety, andeach is hereby expressly made a part of this specification.

BACKGROUND OF THE PRESENT INVENTION

1. Field of the Present Invention

The present invention relates to a coil spring end forming apparatus anda coil spring end forming method. More specifically, the presentinvention relates to a coil spring end forming apparatus and a coilspring end forming method for forming a pigtail portion at the end of acoil spring.

2. Description of the Related Art

In a suspension device of an automobile, a combination of a coil springas a spring device and a shock absorber inserted into the inner sidecoil spring is widely used. In such suspension device, a direction of aninput from a tire is not always matched with the axis of the shockabsorber. Each time there is a vibration input from the tire to theshock absorber, a lateral load acts on the shock absorber. The lateralload acts between a piston and a cylinder of the shock absorber to causesliding resistance. The riding comfort of the automobile can bedeteriorated and the life of the shock absorber can be shortened.

As a method for solving the above problems, there are a method formounting a coil spring so as to be offset with respect to the axis of ashock absorber and a method for forming pigtail portions having apigtail shape at both ends of a coil spring and offsetting the axes ofthe pigtail portions with respect to the axis of a large-diameterportion of the coil spring.

When a pigtail portion is formed at the end of a coil spring, there iswidely used a pigtail forming apparatus which forms, at the end of asemi-formed spring in a cylindrical coil shape, a pigtail portion as aconical winding portion whose diameter is gradually reduced toward itsedge.

The pigtail forming apparatus typically has a forming jig drivenrotatably and rotated while holding the open end of a cylindrical coilspring, a first engaging structure for fixing the end of the cylindricalcoil spring onto the forming jig while a pigtail portion is formed onthe cylindrical coil spring, and a second engaging structure forengaging and restricting a pigtail portion forming start point of thecylindrical coil spring (Patent Document 1).

In the pigtail forming apparatus, the end of the cylindrical coil springis held by the first engaging structure and the pigtail portion formingstart point is held by the second engaging structure. Then, with the endof the coil spring being held by the first engaging structure and thepigtail portion forming start portion being held by the second engagingstructure, the forming jig is rotated to form the pigtail portion.

There is proposed another pigtail forming apparatus having clamp meansfor releasably clamping the open end of a cylindrical winding portion ofa semi-formed spring; a platform on which the semi-formed spring isplaced horizontally and which can be moved toward or away from the clampmeans and can be moved up or down; a first engaging structure disposedon the platform and performing position regulation in the radiusdirection of the end winding portion of the semi-formed spring; a secondengaging structure for regulating axial movement of the semi-formedspring with respect to the platform; rotating means for forciblyrotating the clamp means in the winding direction of the semi-formedspring; a first moving means for forcibly moving up the platform in sucha manner that the center axis of the cylindrical winding portion ismoved toward the rotation center of the clamp means in the state thatthe open end of the cylindrical winding portion positioned on the upperside of the semi-formed spring placed on the platform is clamped by theclamp means; and a second moving means for forcefully moving theplatform along the center axis direction of the semi-formed spring(Patent Document 2).

[Patent Document 1] Japanese Patent Application Laid-Open (JP-A) No.2005-349447

[Patent Document 2] Japanese Patent Application Laid-Open (JP-A) No.2003-290860

SUMMARY OF THE PRESENT INVENTION

In both the pigtail forming apparatuses, the end of the semi-formedspring is held by the clamp portion provided near the mandrel andmovement of the semi-formed spring in the axial direction or in theradius direction is regulated by various engaging structures.

The constitution of the pigtail forming apparatuses is complicated. Itis difficult to shorten time from mounting of the semi-formed spring toformation of the pigtail portion.

The present invention has been made to solve the above problems and anobject of the present invention is to provide a coil spring end formingapparatus and a coil spring end forming method, which require noengaging structures for regulating movement of a semi-formed spring inthe axial direction or in the radius direction and can shorten time frommounting of the semi-formed spring to formation of a pigtail portion.

The invention according to a first aspect relates to a coil spring endforming apparatus comprising a pair of horizontally disposed parallelrollers rotated in the same direction and on which is mounted acylindrical coil shaped semi-formed spring that tends toward formationof a pigtail portion at one end thereof; a mandrel which is acylindrical body having an outer diameter smaller than an inner diameterof the semi-formed spring, that is horizontally disposed near one end ofeach of the parallel rollers; a stopper that is provided coaxially andintegrally with the mandrel and receives the one end of the semi-formedspring; a clamp jig provided adjacent to the stopper to be movabletoward or away from the mandrel, that forms a clamp portion with themandrel and the stopper, and that holds the one end of the semi-formedspring in cooperation with the mandrel; and a pusher that pushes thesemi-formed spring toward the stopper on the parallel rollers, whereinin a state in which the axis of the mandrel is positioned between theaxes of the parallel rollers and the axis of the semi-formed spring, theclamp portion holds one end of the semi-formed spring at an inner sideof a triangle formed by the axes of the parallel rollers and thesemi-formed spring and rotates around the axis of the mandrel in awinding direction of the semi-formed spring to form the pigtail portionat one end of the semi-formed spring.

When the pigtail portion is formed on the semi-formed spring, the end ofthe semi-formed spring is held by the clamp portion to wind thesemi-formed spring around the mandrel. The mandrel is offset withrespect to the semi-formed spring and the mandrel is rotated around theaxis in the state that the semi-formed spring is clamped by the clampportion. The semi-formed spring receives a force in a direction ofrotating in the same direction as the rotational direction of themandrel around the portion held by the clamp portion. Accordingly, aforce extending outward is caused to the semi-formed spring.

As described above, in the coil spring end forming apparatus, the axisof the mandrel is positioned between the axes of the parallel rollersand the axis of the semi-formed spring and the pigtail portion formingstart position is on the inner side of the triangle formed by two axesof the parallel rollers and the axis of the semi-formed spring. Theforce extending the semi-formed spring outward caused by forming thepigtail portion on the semi-formed spring is received by at least oneparallel roller. This can prevent the semi-formed spring from extendingoutward.

The end on the side forming the pigtail portion of the semi-formedspring is firmly held by the clamp portion. The semi-formed spring isnot moved backward from the clamp portion during formation of thepigtail portion.

Accordingly, the coil spring end forming apparatus requires no engagingstructures for regulating movement of the semi-formed spring in theaxial direction or in the radius direction. The use of the coil springend forming apparatus can reduce time required for the engagingstructure to be moved toward or away from the semi-formed spring,thereby improving productivity.

The invention according to a second aspect relates to the coil springend forming apparatus according to the first aspect, wherein the clampportion is rotated around the axis of the mandrel and, at the same time,the clamp portion or the parallel rollers are relatively moved up ordown to form the pigtail portion at one end of the semi-formed spring.

In the coil spring end forming apparatus, by setting the amount ofmovement of the clamp portion, both a coil spring having a pigtailportion axis at an identical position with the axis of the centerportion of the semi-formed spring and a coil spring having a pigtailportion axis offset to the axis of the center portion of the semi-formedspring can be easily produced with high productivity.

The invention according to a third aspect relates to the coil spring endforming apparatus according to the first aspect, wherein when thesemi-formed spring is clamped by the clamp portion, the pusher is movedaway from the semi-formed spring.

In the coil spring end forming apparatus, when the semi-formed spring isclamped by the clamp portion, the pusher is moved away from thesemi-formed spring. When the pigtail is formed on the semi-formedspring, the next semi-formed spring can be loaded immediately, and thus,production efficiency can be improved.

The invention according to a fourth aspect relates to a coil spring endforming method comprising: placing a semi-formed spring in a cylindricalcoil shape that tends toward formation of a pigtail portion at one endthereof on a pair of horizontally disposed parallel rollers; pushing thesemi-formed spring using a pusher toward a clamp portion providedadjacent to one end of parallel rollers while the semi-formed spring isrotated in a winding direction by the parallel rollers; bringing the oneend face of the semi-formed spring into contact with a stopper providedat the clamp portion between the axes of the parallel rollers;positioning an axis of a mandrel between the axes of the parallelrollers and the axis of the semi-formed spring so as to hold the one endof the semi-formed spring by a clamp jig provided in the clamp portion,and the mandrel, at an inner side of a triangle formed by the axes ofthe parallel rollers and the semi-formed spring; and rotating the clampportion around the axis of the mandrel along the winding direction ofthe semi-formed spring and winding one end of the semi-formed springaround the mandrel to form the pigtail portion.

As described in the first aspect, in the coil spring end forming method,the axis of the mandrel is positioned between the axes of the parallelrollers and the axis of the semi-formed spring, and the pigtail portionforming start position is on the inner side of the triangle formed bytwo axes of the parallel rollers and the axis of the semi-formed spring.The force extending the semi-formed spring outward caused by forming thepigtail portion on the semi-formed spring is received by the parallelrollers positioned on the opposite side of the clamp portion byinterposing the axis of the mandrel therebetween. The semi-formed springcan be prevented from extending outward.

The end on the side forming the pigtail portion of the semi-formedspring is firmly held by the clamp portion. The semi-formed spring isnot moved backward from the clamp portion during formation of thepigtail portion.

In the coil spring end forming method, it is possible to use the coilspring end forming apparatus having no engaging structures forregulating movement of the semi-formed spring in the axial direction orin the radius direction. Time required for the engaging structure to bemoved toward or away from the semi-formed spring can be reduced toimprove productivity.

The invention according to a fifth aspect relates to the coil spring endforming method according to the fourth aspect, wherein when the pigtailportion is formed at the one end of the semi-formed coil, the clampportion or the parallel rollers are relatively moved up or down whilethe clamp portion rotates around the axis of the mandrel.

As described in the second aspect, in the coil spring end formingmethod, by setting the amount of movement of the clamp portion, both acoil spring having a pigtail portion axis at an identical position withthe axis of the center portion of the semi-formed spring and a coilspring having a pigtail portion axis at an non-identical position withthat of the axis of the center portion of the semi-formed spring can beeasily produced with high productivity.

The invention according to a sixth aspect relates to the coil spring endforming method according to the fourth or fifth aspect, wherein when theone end of the semi-formed spring is held by the clamp portion, thepusher is moved away from the semi-formed spring to form the pigtailportion.

As described in the third aspect, in the coil spring end forming method,when the semi-formed spring is clamped by the clamp portion, the pusheris moved away from the semi-formed spring. When the pigtail is formed onthe semi-formed spring, the next semi-formed spring can be loadedimmediately, and consequently, production efficiency can be improved.

As described above, according to the present invention, there areprovided a coil spring end forming apparatus and a coil spring endforming method which require no engaging structures for regulatingmovement of a semi-formed spring in the axial direction or in the radiusdirection and can reduce the time from mounting of the semi-formedspring to formation of a pigtail portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view showing the constitution of a coil spring endforming apparatus according to Embodiment 1;

FIG. 2 is an end face view showing the constitution of the coil springend forming apparatus according to Embodiment 1;

FIG. 3 is an explanatory view of the coil spring end forming apparatusshown in FIGS. 1 and 2 showing the operation of parts until asemi-formed spring placed on parallel rollers is pushed onto a stopperby a pusher;

FIG. 4 is an explanatory view of the coil spring end forming apparatusshown in FIGS. 1 and 2 showing the operation of parts until thesemi-formed spring placed on the parallel rollers is pushed onto thestopper by the pusher;

FIG. 5 is an explanatory view of the coil spring end forming apparatusshown in FIGS. 1 and 2 showing the operation of parts when one end ofthe semi-formed spring is held by a clamp portion;

FIG. 6 is an explanatory view of the coil spring end forming apparatusshown in FIGS. 1 and 2 showing the operation of parts when one end ofthe semi-formed spring is held by the clamp portion;

FIG. 7 is an explanatory view of the coil spring end forming apparatusshown in FIGS. 1 and 2 showing the operation of parts immediately afterformation of a pigtail portion is started;

FIG. 8 is an explanatory view of the coil spring end forming apparatusshown in FIGS. 1 and 2 showing the operation of parts immediately afterformation of the pigtail portion is started;

FIG. 9 is an explanatory view of the coil spring end forming apparatusshown in FIGS. 1 and 2 showing the operation of parts during formationof the pigtail portion;

FIG. 10 is an explanatory view of the coil spring end forming apparatusshown in FIGS. 1 and 2 showing the operation of parts during formationof the pigtail portion;

FIG. 11 is an explanatory view of the coil spring end forming apparatusshown in FIGS. 1 and 2 showing the operation of parts during formationof the pigtail portion;

FIG. 12 is an explanatory view of the coil spring end forming apparatusshown in FIGS. 1 and 2 showing the operation of parts during formationof the pigtail portion;

FIG. 13 is an explanatory view of the coil spring end forming apparatusshown in FIGS. 1 and 2 showing the operation of parts at completion offormation of the pigtail portion; and

FIG. 14 is an explanatory view of the coil spring end forming apparatusshown in FIGS. 1 and 2 showing the operation of parts at completion offormation of the pigtail portion.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

As shown in FIGS. 1 and 2, a coil spring end forming apparatus 100according to Embodiment 1 has a clamp portion 2, a rotation drivingportion 4 for rotating the clamp portion 2 around an axis A-A, a base 6for supporting the rotation driving portion 4, a pair of parallelrollers 8 provided adjacent to the rotation driving portion 4 andsupported horizontally and in parallel with each other, a platform 10for supporting the parallel rollers 8 from below, a pusher 12 providedacross the parallel rollers 8 and relative to the clamp portion 2, andan actuator 14 fixed above the platform 10 and moving the pusher 12toward or away from the clamp portion 2.

As indicated by arrows d, the platform 10 is supported by the base 6 soas to be moved up or down. The base 6 has a ball screw mechanism 16 formoving the platform 10 up or down, and a vertical guide mechanism 18 forsupporting the platform 10 for up or down movement and verticallyguiding it. The ball screw mechanism 16 and the vertical guide mechanism18 are relatively provided to interpose the platform 10 therebetween.FIG. 1 shows the constitution of the platform 10 and the ball screwmechanism 16 and the vertical guide mechanism 18 is omitted.

The platform 10 has a motor 8A for rotatably driving the parallelrollers 8 and a timing belt 8B for transmitting the rotational force ofthe motor 8A to the two parallel rollers 8.

The clamp portion 2 has a cylindrical stopper 20 on which a cylindricalsemi-formed spring 30 placed on the parallel rollers 8 abuts, a mandrel22 protruded in the center portion of the end face of the stopper 20coaxially with the stopper 20, and a clamp jig 24 provided on the endface of the stopper 20 so as to be moved toward or away from the mandrel22 and holding the end of the semi-formed spring 30 in cooperation withthe mandrel 22. The clamp portion 2 is formed in such a manner that whenthe stopper 20 and the mandrel 22 are rotated around the axis A-A, theclamp jig 24 is rotated integrally.

The rotation driving portion 4 has a body 4A provided on the base 6 soas to be moved toward or away from the parallel rollers 8 in thedirection of arrows a and rotatably supporting the clamp portion 2around the axis A-A, a driving motor 4B for rotating the clamp portion 2around the axis A-A, and a power transmission supporting portion 4C forfixing the driving motor 4B above the body 4A and incorporating atransmission mechanism (not shown) for transmitting the rotational forceof the driving motor 4B to the clamp portion 2. The base 6 has a movingmechanism (not shown) for moving the body 4A in the direction shown by apair of arrows.

The ball screw mechanism 16 has a ball screw 16A rotated by a motor 16Dfixed to the base 6, a nut portion 16B fixed to the side surface of theplatform 10 and threaded to the ball screw 16A, a ball screw supportingportion 16C fixed to the base 6 and vertically supporting the lower endof the ball screw 16A, and a timing belt 16E for transmitting therotational force of the motor 16D to the ball screw 16A. When the motor16D is rotated, the timing belt 16E transmits the rotational force ofthe motor 16D to the ball screw 16A to rotate the ball screw 16A. Thenut portion 16B is moved up or down so that the platform 10 to which thenut portion 16B is fixed is also moved up or down.

The vertical guide mechanism 18 has a rail 18B provided vertically, amoving head 18A fixed to the side surface on the opposite side of theside provided with the nut portion 16B on the platform 10 and running onthe rail 18B, and a rail support 18C erected vertically on the base 6and supporting the rail 18B. When the platform 10 is moved up or down bythe ball screw mechanism 16, the elevating head 18A fixed to theplatform 10 runs on the rail 18B to vertically guide the platform 10.The platform 10 is moved up or down in the state that its top surface isheld horizontally.

The operation of the coil spring end forming apparatus 100 will bedescribed using FIG. 3 and thereafter. In FIG. 3 and thereafter, therotation driving portion 4, the base 6, and the platform 10 are omitted.

As shown in FIGS. 3 and 4, the parallel rollers 8 are rotated in thecounterclockwise direction in the state that the semi-formed spring 30is placed on the parallel rollers 8 to rotate the semi-formed spring 30in the clockwise direction, as indicated by an arrow b, and the pusher12 pushes the semi-formed spring 30 toward the stopper 20. The axis ofthe mandrel 22, that is, the axis A-A of the stopper 20 is positionedbelow an axis B-B of the semi-formed spring 30.

When one end of the semi-formed spring 30 is inserted between themandrel 22 and the clamp jig 24, as shown in FIGS. 5 and 6, rotation ofthe parallel rollers 8 is stopped to hold one end of the semi-formedspring 30 by the mandrel 22 and the clamp jig 24. As shown in FIG. 5,the position holding the semi-formed spring 30 by the stopper 20 and theclamp jig 24 is on the inner side of a triangle T formed by the axis B-Bof the semi-formed spring 30 and the axes of the two parallel rollers 8.After one end of the semi-formed spring 30 is held by the mandrel 22 andthe clamp jig 24, the pusher 12 may be moved away from the other end ofthe semi-formed spring 30, or as shown in FIG. 5 and thereafter, it mayremain contact with the other end of the semi-formed spring 30.

After one end of the semi-formed spring 30 is held by the mandrel 22 andthe clamp jig 24, as shown in FIGS. 7 and 8, rotation around the axisA-A of the stopper 20 of the clamp portion 2 is started. As indicated byan arrow c, the rotational direction of the clamp portion 2 is thewinding direction of the semi-formed spring 30, that is, the clockwisedirection. When rotation of the clamp portion 2 is started, as shown inFIG. 7 and thereafter, the force in a direction of bending inward by theclamp jig 24 and the mandrel 22 is exerted on one end of the semi-formedspring 30. The semi-formed spring 30 is rotated in the direction of thearrow b around the portion sandwiched between the clamp jig 24 and themandrel 22 to exert a reaction force F in the direction extendingoutward on one or both of the parallel rollers 8. The reaction force Fis received by the parallel rollers 8 to prevent the semi-formed spring30 from extending outward.

When rotation of the clamp portion 2 is started, as shown in FIGS. 9 to12, the clamp portion 2 is rotated around the axis A-A, and the ballscrew mechanism 16 moves down the platform 10 and moves up the clampportion 2 relative to the parallel rollers 8. The axis A-A of thestopper 20 is moved toward the axis B-B of the semi-formed spring 30. Apigtail portion can be formed in a predetermined position at one end ofthe semi-formed spring 30. By moving down the platform 10 and moving therotation driving portion 4 relative to the base 6 so as to move theclamp portion 2 closer to the parallel rollers 8, a flat seat normal tothe axis B-B of the semi-formed spring 30 can be formed at the end ofthe pigtail portion.

As shown in FIGS. 13 and 14, when the clamp portion 2 is rotated throughone revolution, holding of the semi-formed spring 30 by the mandrel 22and the clamp jig 24 is released to take out the semi-formed spring 30having the pigtail portion formed at one end. In FIGS. 13 and 14, in thesemi-formed spring 30, the pigtail portion is substantially coaxial withthe center portion. The axes of the pigtail portion and the centerportion of the semi-formed spring 30 may be offset to each other. Theposition relation between the pigtail portion and the center portion canbe set by an amount of moving-up of the clamp portion 2.

As described above, in the coil spring end forming apparatus 100according to Embodiment 1, the force extending the semi-formed spring 30outward is received by one or both of the parallel rollers 8. Noengaging structures for regulating movement of the semi-formed spring 30in the radius direction are required. One end of the semi-formed spring30 is securely held by the mandrel 22 and the clamp jig 24 duringformation of the pigtail portion and cannot be moved longitudinally. Noengaging structures for regulating movement of the semi-formed spring 30in the axial direction are required.

EXPLANATION OF REFERENCE NUMERALS

2 Clamp portion

4 Rotation driving portion

6 Base

8 Parallel roller

10 Platform

12 Pusher

14 Actuator

16 Ball screw mechanism

20 Stopper

22 Mandrel

24 Clamp jig

30 Semi-formed spring

100 Coil spring end forming apparatus

What is claimed is:
 1. A coil spring end forming apparatus comprising: apair of horizontally disposed parallel rollers that rotate in the samedirection and on which is mounted a cylindrical coil-shaped semi-formedspring that tends toward formation of a pigtail portion at one endthereof; a mandrel, which is a cylindrical body having an outer diametersmaller than an inner diameter of the semi-formed spring, that ishorizontally disposed near one end of the parallel rollers; a stopperthat is provided coaxially and integrally with the mandrel and receivesthe one end of the semi-formed spring, wherein a relative position ofthe stopper and the mandrel does not change; a clamp jig that isprovided adjacent to the stopper so as to be movable toward or away fromthe mandrel, that forms a clamp portion with the mandrel and thestopper, and that holds the one end of the semi-formed spring incooperation with the mandrel; and a pusher that pushes the semi-formedspring toward the stopper on the parallel rollers, wherein the axis ofthe mandrel is offset from the axis of the semi-formed spring and staysat an inner side of a triangle formed by the axes of the parallelrollers and the semi-formed spring during the formation of the pigtailportion, and wherein the coil end forming apparatus is configured suchthat, in a state in which the axis of the mandrel is positioned betweenaxes of the parallel rollers and an axis of the semi-formed spring: theclamp portion holds the one end of the semi-formed spring at the innerside of the triangle; and the clamp portion rotates around the axis ofthe mandrel in a winding direction of the semi-formed spring to form thepigtail portion at the one end of the semi-formed spring.
 2. The coilspring end forming apparatus according to claim 1, wherein the clampportion rotates around the axis of the mandrel and, at the same time,the clamp portion or the parallel rollers are relatively moved up ordown to form the pigtail portion at the one end of the semi-formedspring.
 3. The coil spring end forming apparatus according to claim 1,wherein when the semi-formed spring is clamped by the clamp portion, thepusher is moved away from the semi-formed spring.
 4. The coil spring endforming apparatus according to claim 2, wherein when the semi-formedspring is clamped by the clamp portion, the pusher is moved away fromthe semi-formed spring.